1. Field of the Invention
The present invention relates to an aqueous high concentration surfactant slurry containing an olefin sulfonate. More specifically, it relates to an aqueous high concentration olefin sulfonate surfactant slurry having a decreased viscosity, which is easily handled and pumped at room temperature.
2. Description of the Related Art
Olefin sulfonates having an alkyl group with 12 to 20 carbon atoms suitable for use as a raw material for home and industrial detergents are generally used in the form of a slurry containing about 40% or less of the olefin sulfonates, to obtain an easy to handle slurry having a uniform quality. However, a higher concentration slurry has been desired from the standpoints of the decrease in the temperature and the packaging costs and also of improvements in the efficiency of storage.
When the olefin sulfonate concentration in an aqueous olefin sulfonate slurry is approximately 40% by weight or more, the viscosity of the olefin sulfonate slurry is rapidly increased to form a gellation and thus lose fluidity. When the olefin sulfonate concentration is further increased to, for example, 60% to 70% by weight, the viscosity is gradually decreased between these ranges, but the fludity of the slurry is still very poor. Therefore, an aqueous high concentration olefin sulfonate slurry having a low viscosity is strongly required in the art from the standpoints of the handling and pumping transportation thereof. Typically, an aqueous olefin sulfonate slurry having a viscosity of 150 poise or less at room temperature (i.e., 25.degree. C.) is commercially important in view of the thermal insulation or maintenance of temperature and the necessary costs during the storage thereof.
Various attempts have been heretofore made to decrease the viscosity of an aqueous high concentration slurry of olefin sulfonates. For example, the addition of sodium formate (e.g., U.S. Pat. No. 4,003,875) and the addition of polyethylene glycol or polyoxyethylene alkyl ether in combination with aromatic carboxylate (i.e., salt) (e.g., Japanese Unexamined patent publication (Kokai) No. 58-157758) have been proposed. However, these additives can prevent the gellation of the high concentration slurry only at an elevated temperature. These additives cannot decrease the viscosity of the aqueous high concentration slurry of olefin sulfonates at room temperature to an extent such as commercially required, since the slurry is solidified at room temperature or because the desired fluidity cannot be obtained at room temperature.
In addition, Japanese Unexamined Patent Publication (Kokai) No. 52-78828 proposes the production of an aqueous high concentration slurry of olefin sulfonates by adding an excess amount of an alkaline substance and an alkylene oxide. However, the high concentration slurry thus obtained has a disadvantage in that special precautions must be taken during handling due to the high pH thereof and that the slurry must be neutralized when used. As a result, a large amount of salts are produced as by-products. Especially when the aqueous high concentration slurry is used as a starting material for liquid detergents, shampoos, or the like, the usable amount of the slurry is inherently limited to avoid worsening the liquid property of the product. Thus, according to existing techniques, there are large limitations in the utility thereof and, moreover, the desired decrease in the viscosity of the aqueous high concentration slurry of olefin sulfonates at room temperature has not been accomplished as yet.